1. Field of the Invention
The invention relates to a method of processing mailpieces, in which a digital image of a surface of a current mailpiece is formed for the purpose of using Optical Character Recognition (OCR) to recognize a recipient postal address for said current mailpiece, and, if it is determined that the recognized recipient address corresponds to an incorrect recipient address, a forwarding address is placed on said surface of the current mailpiece.
2. Discussion of the Background Art
Such a method of processing mailpieces, with account being taken of mailpieces that are to be forwarded, is known, for example, from Patent Documents WO2005/049232, EP0949014, and EP0500180. Taking account of mailpieces that are to be forwarded can also be referred to as “readdressing”. In a batch of mailpieces to be processed in a sorting machine, it is generally necessary to forward a fraction, of the order of a few percent, of the mailpieces. A mailpiece can need readdressing due to a change of address of the recipient of the mailpiece. The forwarding process is triggered for recipients that have asked the postal operator in charge of the inward sorting to forward their mail.
A conventional sorting process takes place as follows. A batch of mailpieces is put through a machine a first time, i.e. in a first sorting pass, for the purpose of using OCR to recognize the addresses of the recipients, and each mailpiece is directed to a sorting outlet of the machine. At the same time, each mailpiece is assigned a unique identification number that is placed on the surface of the mailpiece in the form of a barcode. During the second sorting pass, i.e. while each mailpiece is passing, for a second time, through the same sorting machine or through some other machine, said bar code is read back so as to retrieve the recipient address for the mailpiece in such a manner as to direct the mailpiece to the corresponding sorting outlet of the machine. If the mailpiece bears a recipient address that is incorrect, e.g. due to a change of address of the recipient about which the postal operator has been informed, then, during the first sorting pass, processing is applied that consists firstly in detecting, during the first sorting pass, that the recipient address recognized by OCR is an incorrect address (by scanning through a list of predetermined incorrect addresses kept by the postal operator and stored in the machine), and in placing a forwarding address (retrieved from the above-mentioned list of addresses or on the basis thereof) on the surface of the mailpiece (e.g. by printing it on a label). While this mailpiece to be forwarded is on its second sorting pass, the bar code is read back from the surface of the mailpiece so as to retrieve the identification number of the mailpiece, which number serves as an index for retrieving the forwarding address from a database so as to direct the mailpiece to the appropriate sorting outlet.
A technique is also known for virtually identifying the mailpieces that consists in deriving digital signatures from the images of the mailpieces, those signatures then serving as unique identifiers for the mailpieces. In that technique, while a mailpiece is undergoing a first sorting pass, and on the basis of the image of the surface of the mailpiece that bears the recipient postal address of the mailpiece, a digital signature (a kind of a graphical fingerprint) is derived that comprises a first component or “image component” representative of physical characteristics of the digital image of the mailpiece and a second component or “postal component” indicating at least the spatial position of the recipient address block present in the image of the mailpiece. These two components should not be correlated relative to each other. In particular, the image component is formed by “global” attributes that are representative of overall physical characteristics taken from the entire set of picture elements (pixels) of the digital image of the mailpiece. The image component is also formed of second attributes or “local” attributes that are representative of local physical characteristics taken from distinct portions of a grid applied over the image of the mailpiece (or of a plurality of different grids).
That digital signature is used as an index for retrieving OCR-recognized address information from a database. While the same mailpiece is undergoing a second sorting pass, an image of the surface of the mailpiece is formed again for the purpose of deriving a current signature that is compared with the candidate signatures recorded during the first sorting pass of the mailpieces. If it is detected that said current signature and a candidate signature match, i.e. coincide, it is then possible to retrieve said address information from said database so as to direct the mailpiece to the appropriate sorting outlet. That technology offers the advantage, in particular, of reducing the operating costs of a postal sorting machine by obviating the need for bar codes as descried in French Patent Document FR-2 841 673.
Unfortunately, in practice, that virtual mailpiece identification technique cannot be used directly in the presence of mailpieces to be forwarded because, between two sorting passes, the surfaces of such mailpieces to be forwarded must be modified by placing forwarding addresses that make it possible for the mailpieces to be delivered on a delivery round or “postman's walk”.